kiyori
幼苗
共回答了19个问题采纳率:84.2% 举报
1、
x1+x2=-5/2
x1x2=-3/2
所以(x1-x2)²=(x1+x2)²-4x1x2
=25/4+6
=49/4
|x1-x2|=7/2
2、
1/x1²+1/x2²
=(x1²+x2²)/x1²x2²
=[(x1+x2)²-2x1x2]/(x1x2)²
=(25/4+3)/(-3/2)
=-37/6
3、
x1³+x2³
=(x1+x2)(x1²-x1x2+x2²)
=(x1+x2)[(x1+x2)²-3x1x2]
=(-5/2)[25/4+9/2]
=-215/8
1年前
5